Thread forming sparkplug gaskets



July 30, 1963 H. P. HoPP 3,099,456

THREAD FORMING SPARKPLUG GAsxETs Filed Aug. 1. 1960 2f l. if

United States Patent O 3,099,456 THREAD FORMING SPARKPLUG GASKET Harold I. Hopp, 374 Lantana Ave., Englewood, NJ. Filed Aug. 1, 1960, Ser. No. 46,540 Claims. (Cl. 277-166) This invention relates generally to sealing gaskets, and more particularly to an improved spark plug gasket of a self-locking type.

In my co-pending application, Serial No. 21,317, filed April 1l, 1960, entitled Self-Locking Spark Plug Gaskets, there is disclosed a spark plug `gasket which may be slipped over a threaded cylindrical portion at the lower end of the spark plug, and which will permanently secure itself upon the plug once the plug has been tightened within a -threaded spark plug opening in a cylinder head of an internal combustion engine. The present disclosure relates to a gasket of this -type which may be slipped over a threaded cylindrical portion, but which upon the tightening of the plug Within a cylinder head will mainltain itself upon the threaded portion in such manner that cross threading may occur with respect to the threads on the plug, so that the gasket may be manually unthreaded from the plug when desired, but which will maintain itself upon -the plug until intentionally removed.

Spark plug gaskets, in (the prior art, have been of a deformable type, usually stamped from copper or copperplated steel. When a spark plug is engaged Within a cylinder head, the gasket is deformed under compression to effect a seal between the spark plug and the cylinder head. Upon removal of the spark plug for cleaning or replacement, the conventional gasket has usually remained on the exposed surface of the cylinder head, necessitating separate removal before a new gasket may be employed to seal the replaced plug.

In recent years, the wide use of overhead valve type internal `combustion engines has made the replacement of spark plugs a far more diflicult operation than has heretofore been the case. In many cases, the spark plug opening in the head is completely concealed from view of the mechanic, and the spark plug and attached gasket must be manually inserted blindly into the proper opening using the fingers of one hand. Such operations have resulted in the loss `of gaskets prior to engagement of the spark plug with the opening inthe cylinder head, and, in some instances, the replacement of a spark plug with a new gasket disposed upon an old one, sol that the spark plug does not become properly seated with respect to the combustion chamber.

Attempts have ybeen made `to provide so-called screwon type gaskets having projections or a continuous thread thereon which permit the gasket to be threadedly engaged upon the lower cylindrical portion of the spark plug body, so that the same will remain in proper position during the engagement of the spark plug with 'the cylinder head. While such construction has been adequate to maintain the gasket upon the spark plug during such engagement, it has tended to remain in place upon the cylinder head when the spark plug is unscrewed, owing to the cementing action'of rust, corrosion and the like which normally occurs While Athe spark plug is in service. Such devices have had an added disadvantage in that a separate operation, that of threading the gasket upon the plug, is necessary before the plug may be installed.

It is lamong hte principal objects of the present invention to provide an improved self-locking gasket which may be conveniently installed upon la spark plug and which will remain positively interconnected with the same during removal of the spark plug from the cylinder head, but which nevertheless may be manual-ly removed when desired once the spark plug has been disconnected from the cylinder head.

ICC

Another object of the invention lies in the provision of a spark plug gasket of the type `described which may be initially engaged upon the threaded cylindrical portion of a spark plug without the necessity of a manual lthreading operation, and in which during the engagement of the plug with a cylinder head, the deformation of the gasket will be such as to reduce the internal diameter of the same to a point where it is less than the outside diameter of the threaded cylindrical portion `of the plug, but which may be cross threaded as a manual operation to permit the gasket to be twisted from engagement with the plug Without damage to either gasket or plug.

A further object Iof the invention lies in the provision of improved self-locking spark plug gasket construction in which the cost of fabrication may be directly comparable with that of constructions existing in the art, thereby permitting consequent wide sale, distribution and use.

A feature of the invention lies in the improved sealing action which is obtained by the gasket construction contemplated by the present invention, as contrasted with prior art devices.

'llhese objects and features, as Well as other incidental ends and advantages, will more fully appear in the progress of the following disclosure, and be pointed out in the appended claims.

In the drawing, to which reference will be made in the specication, similar reference characters have been employed to designate corresponding parts throughout the several views.

FIGURE 1 is a View in elevation of a first embodiment of ythe invention.

FIGURE 2 is a fragmentary sectional view showing the rst embodiment in position upon a conventional spark plug 'and prior Ito installation of the spark plug upon a cylinder head.

FIGURE 3 is a similar sectional view showing the spark plug in installed condition.

FIGURE 4 is Ia fragmentary view in elevation, partly in section, showing the threaded removal of the first embodiment after use.

FIGURE 5 is a fragmentary view in elevation showing the same in deformed condition.

FIGURE 6 is a transverse sectional view as seen from the plane 6 6 in FIGURE 5 FIGURE 7 is a view in elevation corresponding to that seen in FIGURE 5, but showing a second embodiment of the invention.

FIGURE 8 is a `side elevational view thereof as seen from the plane 8 3 in FIGURE 7.

FIGURE 9 is an enlarged fragmentary sectional view as seen from the plane 9 9 in FIGURE 8.

In accordance with the invention, the device, generally indicated by reference character itl, is employed in conjunction With a conventional spark plug 11 having a metallic body l2 including an upper cylindrical member 13 and a lower threaded cylindrical member 14 which `supports. a conventional electrode 15. The continuous thread 16 extends upwardly along the member 14, and meets the upper cylindrical member 13 in a tapered fillet IS. The spark plug is engageable upon a cylinder head I9 having a cup-like recess Ztl, there being a threaded bore Z1 positioned in the center of the recess Ztl. The bore 21 is provided with an upper chamfered portion 22, usually not corresponding in taper to that of the fillet 18. In certain cases, the tapered fillet 18 is omitted, and in such case the device lil may be installed in a position inverted from that seen in FIGURES 2 to 4, inclusive, in the drawing.

Referring to FIGURES 1 and 2, in initial or undistorted form, the device I0 includes an outer peripheral edge surface 25, an inner peripheral edge surface 26, an upper surface 27 and a lower surface 28. The device 10 is preferably formed using a series of progressive stamping dies, as is well known in the art, and includes a rst or outer sealing portion 30, a second sealing portion 31, `a third sealing portion 32 and an inner angularly disposed flange 33. As best seen in FIGURE 5, the last-mentioned flange 33 is provided with a plurality of radially extending slots 35 forming individual segmented portions 36. During the forming operation, the segments 35 may be given a degree of twist about an axis angularly disposed with respect to the normal axis of compression of the gasket, forming non-continuous segments in the edge surface 26 (see FIGURE S).

`In the alternative, the twisting operation may be omitted, and the segments 36 may be permitted to .acquire a similar conguration upon the unthreading manual movement imparted by the user in -removal of the gasket from the plug.

Upon installation as seen .in FIGURE 3, the mating surfaces Hatten the undulations formed by the sealing portions 30-32 to effect a seal `at each crest thereof. Because of the pitch of the undulations, metal is caused to ilow both centrifugally and centripetally, resulting in a reduction of the inner diameter thereof. Since the initial inner diameter prior to compression is just sulieient to clear the major diameter of the thread 16, upon compression the flange 33 is reduced in inner diameter to a point where the same lies between the major and minor diameters of the thread 16.

Upon removal of the spark plug with respect to the cylinder head, as indicated in FIGURE 4, the device can be caused to take on a thread corresponding in pitch to that of the thread 16 owing to the angular disposition of the non-continuous edge 26. This operation requires some manual effort, as the thread is actually formed at the time the gasket is removed, which assures that the gasket will remain upon the plug during the period in which the plug is removed from engagement with the cylinder head.

Turning now to the second embodiment of the invention, as illustrated in FIGURES 7, 8 and 9, parts corresponding to those of the rst embodiment have been designated by similar reference characters with the additional pre-X 1.

The lsecond embodiment differs from the first embodiment in the provision of a plurality of raised projections 39 and alternately spaced depressed projections 40' situated .adjacent the slots 135. In the undeformed state, it is not necessary that the edge 126 be placed in non-planar condition, this occurring when the plug is tightened within the cylinder head and pressure is brought to bear upon the projections 39 and 40 which cause the individual segments to assume `a disposition corresponding to that seen in FIGURE 6.

I wish it to be understood that I do not consider the invention limited to the precise details of structure shown and set forth in this specification, for obvious modifications will occur to those skilled in the art to which the invention pertains.

I claim:

1. In combination, a spark plug having a threaded shank, and a compressible annular gasket having a principal axis of compression; said gasket including a plurality of undulating sealing portions, and an inner flange having at least one radially arranged slot therein forming a segmented inner edge, said inner llange disposed in angular Contact relation with respect to said axis of compression, so that opposite sides of said inner flange are in deformable contacting engagement with opposed surfaces, said inner edge having a diameter which is substantially greater than the major diameter of lsaid threaded shank when said gasket is in a relatively uncompressed state, and suhstantially less than said major diameter when in lrelatively compressed state; whereby said gasket may be slipped upon said shank of said spark plug with a purely translational motion, and may become threadedly aixed to said shank upon the installation and tightening of said spark plug wherein said gasket is compressed.

2. In combination, a spark plug having a threaded shank, and a compressible annular gasket having a principal axis of compression; said gasket including a plurality yof undulating sealing portions, and an inner flange having a plurality of radially arranged slots therein forming `a segmented inner edge, said inner llange disposed in angular contact relation with respect to said axis of compression, so that opposite sides of said inner flange are in deformable contacting engagement with opposed surfaces, said inner edge having a diameter which is substantially greater .than the major diameter rof said threaded shank when said gasket is in a relatively uncompressed state, and substantially -less than said major diameter when in relatively compressed state; whereby said gasket may be slipped upon said shank of said spark plug with a purely rtranslational motion, and may become threadedly allixed to said shank upon the installation and tightening of said spark plug wherein said gasket is compressed.

3. Structure as set forth in claim 2 in which the individual segments of said inner edge are disposed in mutually non-planar relation. j

4. Structure in accordance with claim 2 in which said inner flanges is provided with first and second projections extending outwardly in opposite directions from the planes of said inner flanges.

5. In combination, a spark plug having a threaded shank, and an annular compressible gasket therefor; said gasket having a principal 'axis of compression, a plurality of undulating sealing portions, and an inner flange disposed in angular relation with respect to said axis of compression, said inner lange having at least one radially arranged slot therein forming a segmented inner edge, said inner flange disposed in angular contact relation with respect to said axis of compression, so that opposite sides of said inner flange are in deformable contacting engagement with opposed surfaces, said inner flange having first and second projections thereon extending outwardly in opposite directions from the plane of said inner llange; said inner edge having a diameter substantially greater than the major diameter of said -threaded shank when said gasket is in relatively uncompressed condition, and a diameter substantially less than said major diameter of said threaded shank when in relatively compressed condition; whereby said gasket may be slipped upon said shank of said spark plug with a purely translational motion, and may become threadedly yaffixed to said shank upon the installation and tightening of said spark plug wherein said gasket is compressed.

References Cited in the le of this patent UNITED STATES PATENTS 1,133,320 Rockwood Mar. 30, 1915 1,685,059 Bailey Sept. 18, 1928 2,941,105 `Rickenbach June 14, 1960 3,029,084 Gobb Apr. l0, 1962 FOREIGN PATENTS 431,097 Great Britain July 1, 1935 761,771 Great Britain Nov. 2l, 1956 110,502 Switzerland June 1, 1925 

1. IN COMBINATION, A SPARK PLUG HAVING A THREADED SHANK, AND A COMPRESSIBLE ANNULAR GASKET HAVING A PRINCIPAL AXIS OF COMPRESSION; SAID GASKET INCLUDING A PLURALITY OF UNDULATING SEALING PORTIONS, AND AN INNER FLANGE HAVING AT LEAST ONE RADIALLY ARRANGED SLOT THEREIN FORMING A SEGMENTED INNER EDGE, SAID INNER FLANGE DISPOSED IN ANGULAR CONTACT RELATION WITH RESPECT TO SAID AXIS OF COMPRESSION, SO THAT OPPOSITE SIDES OF SAID INNER FLANGE ARE IN DEFORMABLE CONTACTING ENGAGEMENT WITH OPPOSED SURFACES, SAID INNER EDGE HAVING A DIAMETER WHICH IS SUBSTANTIALLY GREATER THAN THE MAJOR DIAMETER OF SAID THREADED SHANK WHEN SAID GASKET IS IN A RELATIVELY UNCOMPRESSED STATE, AND SUBSTANTIALLY LESS THAN SAID MAJOR DIAMETER WHEN IN RELATIVELY COMPRESSED STATE; WHEREBY SAID GASKET MAY BE SLIPPED UPON SAID SHANK OF SAID SPARK PLUG WITH A PURELY TRANSLATIONAL MOTION AND MAY BECOME THREADEDLY AFFIXED TO SAID SHANK UPON THE INSTALLATION AND TIGHTENING OF SAID SPARK PLUG WHEREIN SAID GASKET IS COMPRESSED. 